1. Field of the Invention
The present invention generally relates to an improved oven for continuously cooking food. In particular, the present oven efficiently cooks food while minimizing heat loss. Known art may be found in U.S. classes 99 and 198 and the subclasses thereunder.
2. Known Art
As will be appreciated by those skilled in the art, restaurants and the like use radiant or convective ovens extensively during food preparation. Ovens can be categorized as either a conveyor type that operates in a steady-state fashion or as a conventional type that operates in a batch wise fashion. Regardless of the type, both are plagued by waste heat that is usually transmitted to the surrounding atmosphere (i.e. the restaurant or other facility). It is desirable to minimize such losses.
In high volume commercial and restaurant operations, conveyor ovens have replaced more traditional baking ovens in some circumstances. A conveyor oven can significantly reduce the amount of cooking time compared to other types of ovens. Conveyor ovens also cook food in a generally healthier manner as well as requiring less training and/or experience for proper use.
Conveyor ovens typically use a stainless steel continuous conveyor belt to carry individual food items through the heated portion of an oven. These ovens have a first opening through which uncooked food enters and a second spaced apart opening on the opposite end of the oven through which cooked food exits. An endless conveyor belt passes through this cooking tunnel and extends past both openings sufficiently to allow safe insertion and retrieval of food products. The only limit to how many identical food items may be placed in the oven and cooked is the speed of the conveyor belt which correlates to the residence time to sufficiently cook the food items. This arrangement allows individual food items to be continuously placed on the conveyor belt for sequential steady state cooking. This is significantly faster than conventional ovens in which each food item must wait its turn since they are cooked batch wise.
In restaurants conducting a high volume of business, the speed of cooking provided by a conveyor oven is often quite advantageous. A conveyor oven usually reduces the preparation time for a food order, which leads to increased customer satisfaction. It may also allow a restaurant to serve a larger number of customers. When the food items offered by a restaurant are to be cooked at the same temperature for the same amount of time, a conveyor oven is particularly advantageous. The operator need only set the temperature and conveyor belt speed as necessary to cook the selected foods. Once these two parameters are set, the oven may be operated continuously without any adjustment. Even a person unskilled in the art of cooking is able to prepare high quality cooked food products simply by placing them on the conveyor belt of this type of oven. The ease of operation and high throughput of conveyor ovens makes them highly desirable in restaurants and other commercial and industrial settings.
A single food order at a restaurant may include a variety of different actual food items. Those skilled in the art of cooking will appreciate that different food items require a variety of different cooking times. However, it is desirable to serve all of the food items in a single food order at the same time. Food items that are prepared quickly may cool significantly while waiting for an accompanying food item to finish cooking. In addition, foods requiring a longer cooking time than accompanying food items may be undercooked so that the other food items are not overly cooled when served.
In an effort to combat these problems, many restaurants use heat lamps to keep food warm while waiting for accompanying food items to finish cooking. This is an imperfect solution. Some food items may remain under a heat lamp for an extended period of time. This causes some food items to dry out. Extended exposure to heat lamps also causes the plate on which the food items rest to become uncomfortably hot. It is also believed that exposure to heat lamps has a deleterious effect on both the flavor and texture of the food items. The use of heat lamps also does not guarantee that all food items will be served at the same temperature. The actual temperature of the food items will depend on how much time they have spent underneath a heat lamp.
It also is well known in the art of cooking that brick or stone ovens provide superior flavor and texture to foods. Connoisseurs of pizzas and breads, as well as fish and meats prefer the qualities that only a stone or brick oven can impart to these food products. However, stone or brick ovens are difficult to operate. Only those well skilled in the art of cooking with these types of ovens can properly bake food items evenly and without burning the food products. This means that a restaurant must pay a higher salary to employ one skilled in stone or brick oven operation. This is an economic disadvantage to a restauraunteur. Additionally, these ovens have traditionally been capable of cooking only one item at a time. This means that individual food orders require more time to prepare since they must be cooked in a batch wise fashion. The skill required by the operator and slow throughput makes these ovens more expensive to operate than conveyor ovens or other conventional ovens. While the food items have superior flavor and texture, they are more expensive and slower than both conventional and conveyor ovens. This results in a higher price for the customer. This also means that a restaurant can not accommodate as many customers and customers must wait a longer period of time for their food orders to be prepared.
In a stone or brick oven, the heat is imparted to the baked food item through the stone or brick surface on which it rests during cooking. It is believed that this heat transfer from a stone-like material to the food item is responsible for the superior flavor and texture of food items prepared in this manner.
Conveyor ovens typically use conveyor belts comprised of stainless steel rods spaced apart by linking elements to mimic the grating found on a grill. In this manner heat is applied directly to the baked food product. This is sufficient to properly cook items and also facilitates cooking methods such as xe2x80x9cflame broiling.xe2x80x9d However, the flavor and texture this grill-style baking imparts to food items is believed to be inferior to that of a stone or brick oven.
It is also well known in the art that food items may be cooked much more quickly when they are fried rather than baked. Unfortunately, flied foods are much less healthy than baked food products. As people and our society in general become more health conscious, there is a greater desire for healthier food items. Although baking is significantly healthier than frying food items, it is a much slower process. This makes baking food items a less desirable cooking method in restaurants having a high volume of business.
It is particularly desirable to replace deep frying in commercial and/or industrial settings where a high volume is necessary. This is especially true with the increasing popularity of pre-prepared meals that are generally prepared by a wholesaler and/or purchasing company for subsequent resale to an end-user who simply reheats the pre-cooked meal. This is thus a need to prepare large volumes of food that previously did not exist.
As mentioned previously, another serious disadvantage of many ovens is their significant output of waste heat. Particularly, when convection heating is used in a conveyor oven, much of the heated air escapes from the entrance and exit openings in the oven. This results in higher overhead costs, a less comfortable work environment for the oven operators, and greater cost in maintaining a comfortable ambient temperature throughout a restaurant.
It is thus desirable to develop a cooking method that allows a variety of food items to be served at the same time and temperature without a reduction in quality.
It is also desirable to develop a healthy method of food preparation capable of high throughput.
It is also desirable to develop a cooking method that imparts both the superior food quality of a stone oven and the significant economic advantages of a conveyor oven.
It is also desirable to develop a cooking method that reduces the amount of waste heat produced by an oven.
Another desirable improvement would be a high throughput volume for an infrared oven sufficient to permit its use in industrial and commercial settings.
It is also desirable to reduce deep frying for industrially and/or commercially prepared foods.
Yet another desirable improvement would be an infrared conveyor oven able to be employed by industrial users to quickly prepare large quantities of food in a healthy manner for subsequent sale to end users as pre-cooked meals.
The present invention overcomes the perceived problems with the known art. The present invention provides an improved oven that utilizes variably powered infrared cooking elements to quickly, efficiently and thoroughly cook various foods while minimizing waste heat. The improved ovens can be in the form of conventional ovens or in the form of a conveyor type oven.
One exemplary embodiment combines the advantages of stone-like ovens and those of conveyor ovens. This embodiment provides a conveyor oven that includes a stone-like conveyor belt. The outside surface of the conveyor belt is made of a stone-like material. This stone-like material is generally actual stone, brick or ceramic material capable of being molded or cut to a desired shape.
A conveyor oven is provided that heats food items from both the top and bottom in the tunnel portion of the oven. Additionally, heat sources may also be placed on the sides of the tunnel portion of the oven. These heating sources may be of any type known in the art, such as convection, flame or infrared radiation. Ideally, the heat sources used provide only infrared radiation generated by either gas powered heat plenums, gas powered porous grates, electric heating coils within the infrared radiation source, or any other method of generating infrared radiation for cooking. These methods of infrared radiation heating are well known in the art. Infrared radiation sources are preferred because of their high efficiency and low amount of waste heat generated. This provides an oven that is less expensive to operate, while also leading to a more comfortable working environment for the operators and lower cost in maintaining a comfortable dining environment.
Infrared radiation heat sources are also known in the art to cook food items from the inside out. This shortens the time required to cook a particular item. This also provides for a baking oven with a significantly greater throughput. This allows high volume restaurants to prepare a large number of food items quickly, in a healthy manner.
The bottom heating element is located within the loop of the continuous conveyor belt. This provides efficient heating of the conveyor belt itself, which then transfers heat to the food items resting upon it. Sufficient heating of the conveyor belt is necessary to facilitate the heat transfer necessary to impart superior quality to the food items.
The conveyor oven has at least one temperature sensing means. Preferably there are two temperature sensing means. One senses the temperature within the tunnel portion of the oven. The second measures either the temperature directly below the upper part of the conveyor belt or the temperature of the upper part of the conveyor belt itself.
The conveyor oven has a temperature controller and thermometers in the tunnel portion of the oven for controlling the cooking temperature therein. This includes means of adjusting the heating element within the loop of the conveyor separately from the heating elements on the top and sides of the tunnel. This ensures the important proper heat transfer rate through the conveyor belt.
The path of the conveyor belt includes at least one support device that may take the form of a shelf ledge or a roller. Because a stone-like conveyor belt is heavy, support must be used to prevent sagging of the belt on its path through the tunnel portion of the oven. The support devices may extend the entire width of the conveyor belt, or may operate only on a portion of the belt. They may be located on the lateral ends of the belt""s pathway, or may be located in the center. The support devices may also include means such as teeth or grooves to maintain the belt on a straight path.
Located on at least the output end and possibly on the input end of the conveyor belt loop is a sprocket. The sprocket includes teeth designed to engage the conveyor belt. The sprocket is powered by a motor sufficiently powerfull to move the conveyor belt at a constant speed through the loop pathway. The present invention also includes a means to adjust the speed of the sprocket, thereby adjusting the speed of the conveyor belt. This in turn adjusts the cooking time of the food items.
The conveyor belt includes a series of stone-like tablets extending the width of the conveyor belt. The tablets are sequentially aligned in the longitudinal direction of the conveyor belt. On both ends of the individual tablets are bracket assemblies. These bracket assemblies include a means of attachment to the tablet, a means of connecting to the bracket assembly on the opposite end of the same tablet and a means of rotatably attaching to bracket assemblies in front of and behind it. Alternatively, tablets may be directly connected to one or more drive chains.
Successive tablets may fit together in a tongue and groove fashion. The forward facing ends of the tablets have a downward wedge shape while the backward facing ends have an upward wedge shape. This provides a continuous, rather than a grated, surface for the food to be cooked on. This increases the heat transfer from the tablets to the food items and decreases the heat transfer directly from the heat source to the food items.
In another exemplary embodiment, there is also provided a conveyor oven having automatically adjusting infrared heating elements. Means are provided for detecting when a food item enters the oven. Upon detection of such a food item, the heating elements within the oven automatically turn on. The oven automatically determines when the food item exits the oven.
Upon exit of the food item, the heating elements automatically turn off. This greatly increases energy efficiency and conservation. In addition, the reduced waste heat provides for a more comfortable environment for the oven operators. A more comfortable ambient temperature is also more easily maintained in the absence of excess of waste heat.
In another exemplary embodiment, it is desirable to utilize the foregoing stainless steel conveyor oven with infrared heating elements to improve the throughput of commercial and/or industrial facilities. The conveyor oven permits many foods to be cooked quickly and healthily. Of course, this embodiment is necessarily sized larger to handle larger volumes of food. This embodiment extends the usefulness of the oven to industrial and commercial users as well. Such users are often interested in selling pre-cooked meals to consumers for in-home consumption.
In another exemplary embodiment, there is provided a conveyor oven having infrared heating means for the final preparation of several items. Food items that have completed cooking in different amounts of time, are placed in infrared heating conveyor oven. In this manner, all of the food items are heated to the same temperature for the same amount of time. Because the infrared heating elements heat food items from the inside out, over cooking and drying out of food items is avoided. Food items prepared using this infrared re-heating oven retain their texture and flavor. This offers a significant advantage over the use of heating lamps.
Thus, a principal object of the present invention is to provide an efficient oven that produces significantly less waste heat than other types of ovens.
It is another object of this invention to provide an oven that incorporates the efficiency, ease of use and speed of a conveyor oven with the superior cooking qualities of a stone oven.
It is a further object of this invention to provide a conveyor belt for use in a conveyor oven partially made of a stone-like material.
It is a further object of this invention to provide a conveyor oven in which heat from the heat source is not transferred directly to the food item but rather indirectly through a heat medium located on the conveyor belt.
It is a further object of this invention to provide an oven that produces superior cooked food items with a minimum of waste heat.
It is a further object of this invention to provide a high throughput method of baking healthy food items.
It is a further object of this invention to provide a method of serving multiple food items at the same time, at the same temperature, without a reduction in food quality.
Yet another object of the present invention is the provision of an industrial sized infrared conveyor oven that may be used for the preparation of pre-cooked meals for consumers.